During drilling operations, a drilling fluid, which may also be referred to as drilling mud, is circulated through the wellbore to cool the drill bit, to convey rock cuttings to the surface, or to support the wellbore against collapse of the wellbore and against intrusion of fluids from the formation, among other purposes. Drilling fluids are formulated to have certain fluid characteristics, such as density and rheology, for example, that allow the drilling fluid to perform these functions. However, under certain extreme downhole conditions, such as excessive temperature, for example, some of the properties of the drilling fluid may be altered. For example, the drilling fluid may thicken, increase in viscosity, or form a gel. These changes in properties of the drilling fluid can lead to problems such as solids settling, stuck pipes, and excessive pump pressure.
Drillers counteract these issues by adding thinners, which are sometimes referred to as mud thinners, to the drilling fluid. Some of the more common drilling fluid thinners include plant tannins, such as quebracho, lignosulfonic acid and its salts (e.g., chromium, iron, cobalt, sodium, and aluminum salts or any mixture of these salts), lignitic materials, and polyphosphates. Certain synthetic polymers have also been used as thinners for drilling fluids. However, there is an ongoing need for drilling fluid thinners and/or additives that are capable of withstanding extreme downhole conditions.